# Commonly used and basic commands in SAC

:::warning
Learning resources
https://web.mst.edu/~sgao/manuals/sac_manual.pdf
http://geophysics.eas.gatech.edu/people/zpeng/Teaching/Sac_Tutorial_2006/
https://moodle.glg.miamioh.edu/brudzimr/tutorials/SAC/
https://seisman.github.io/SAC_Docs_zh/
https://ds.iris.edu/files/sac-manual/manual/tutorial.html

:::

## Installation
Please refer to [installation tutorial](https://hackmd.io/@kmo/notes_sac_install)

## Read, sort, and plot SAC files

**Read files**
`r *.SAC` read all file end with .SAC
`r more` read more

**Rearrange**
`sort x` sort by x (attributes in sac file)
`sort distance` sort by distance
`sort a` sort by "a" marker
**Parser**
`rtr` remove trend
`rmean` remove mean
`int` intergrate onece (積分) acc.-> vel.->disp.
`dif` differentiate (微分) disp.-> vel-> acc.

`cut 10 50` `cut o+10 o+50` cut the data from 10 to 50 (values in x axis)
`r *.sac` read the files that need to be cut after cut command

**Display**
`qdp off` turn off quick dirty plot, for finer resolution

`xlim t1 -5 t3 +50` show range of x axis from t1-5 to t3+50 (command before ppk or p)
`xlim o -10 +20` show range from o-10 to o+20
**Plot**
`p` plot by default (one file on one page)
`p1` plot all files, which has been read, in 1 page

## Filter waveforms
`bp` band pass
`lp`,`hp` low pass and high pass

`bp n 4 p 2 c 0.02 0.08`
n 4 : channel
p 2 : pole
c 0.02 0.08: frequecny range (Hz)

## Mark time on waveforms

`ppk p 3 m on` ppk -> picking mode; p 3 -> one page 3 files; m on -> makeall on (mark all file at the same time)
`ppk p 4` picking mode, show 4 files, mark one by one

`a`,`t1`...`t5` markers
`n` next page
`b` back to the last one page

Use mouse to pick two time points for zooming in
`x` zoom out
`k` temporally quit
:::danger
`wh` write all the change during this round; save the header
`q or quit` exit (no change will be made and exit)
:::
## Write files
`w over` overwrite the file that is in read now with the same file name
`w newname.SAC` write/save as a newfile.SAC
`w append .bp` write as a new file, using original name append with ".bp"

## List SAC headers
`lh` list all headers after read files
`saclst kztime kzdate stlo stla stel delta a t1 o f *`
list noted headers from file(f) *
`saclst evlo evla gcarc kzname f *| sort -nk2` combined with sorting command in linux, sort the second column (i.e., evlo here) `-r` list reversely

>For SAC header variables, please check:
https://ds.iris.edu/files/sac-manual/manual/file_format.html

## Write header in SAC files

`chhdr`

---
# Advanced commands

* Convert data between SAC binary and ASCII files
* Write macro file for batch processing: macro *.m
* generate function
`fungen` or `fg` generate function
`FG IMPULSE NPTS 100 DELTA 0.1`

`fft`
`plotsp` or `psp` plot spectrum `psp am` plot amplitude
`convolve` do convolution with the first file
`correlate` do cross correlation wtih the first file

---
# Plot SAC with GMT

## map view plotting

## seismogram and profiles

---
TauP: travel time calculation
>http://geophysics.eas.gatech.edu/people/zpeng/Teaching/EAS8803_S08/ttime/
>

---
SAC> syn
SAC> ppk p 5 m on 
SAC> sss
 Signal Stacking Subprocess.
SAC/SSS> prs
SAC/SSS> hp cor 1